Association between PIK3CA Mutations in Blood and Tumor-Infiltrating Lymphocytes in Peruvian Breast Cancer Patients

Area of Science:

• Oncology
• Molecular Diagnostics
• Genetics

Background:

• Breast cancer is a significant health concern globally, with distinct molecular subtypes influencing prognosis.
• Circulating tumor DNA (ctDNA) analysis offers a non-invasive method to detect tumor-specific alterations.
• Tumor-infiltrating lymphocytes (TILs) are immune cells within tumors that impact breast cancer outcomes.

Purpose of the Study:

• To investigate the prevalence of PIK3CA mutations in ctDNA among Peruvian breast cancer patients.
• To explore the association between ctDNA PIK3CA mutations and tumor characteristics, specifically TIL levels.
• To evaluate the potential of ctDNA PIK3CA mutations as a prognostic marker for breast cancer outcomes.

Main Methods:

• Prospective study at Instituto Nacional de Enfermedades Neoplasicas, Peru, analyzing plasma samples from 183 breast cancer patients.
• Evaluation of TIL levels and detection of PIK3CA mutations in ctDNA.
• Correlation analysis of ctDNA findings with clinical characteristics, tumor phenotype, stage, recurrence, and survival data.

Main Results:

• PIK3CA mutations were detected in 35% of ctDNA samples, predominantly the E545K variant.
• ctDNA PIK3CA mutations were significantly associated with lower TIL levels (p=0.04).
• A trend was observed between ctDNA PIK3CA presence and advanced stages (p=0.09), higher recurrence rates (p=0.053), and shorter survival (p=0.083).

Conclusions:

• PIK3CA mutations in ctDNA are frequently observed in Peruvian breast cancer patients.
• The presence of ctDNA PIK3CA mutations is linked to reduced TIL levels.
• ctDNA PIK3CA mutations may serve as a predictive marker for adverse outcomes in breast cancer.